On Mon, 06 Dec 2010 23:39:14 -0500, Bill wrote:

wrote:
On 07 Dec 2010 03:36:02 GMT, (Scott Lurndal)
wrote:

writes:
Scott Lurndal wrote:

There is no such thing a "12-3 THHN".


Someone else wrote "pull 12-3 w/ground THHN". Is that more acceptable
(I understood what he was trying to tell me--2 hots, a common and a ground)?


When wire is referred to with a hyphen (e.g. 12-3), that means that there are
three AWG12 conductors encased in an outer jacket. Typically, such cables
are type "NM" (non-metallic sheathed) or "UF" (underground feeder). w/G adds
a non-jacketed conductor in the outer jacket that is designated the grounding
conductor. Most XX-3 w/g cables include red, black, white and unjacketed
conductors.

THHN is a wire "type" code used for single conductors that are routed typically
through some form of chase (electrometallic tubing (EMT) or nonmetallic tubing,
wiremold raceway, etc.).

THHN may not be used without an enclosing raceway of some form (note that if
your light fixtures are mounted end-to-end and there is a nipple or length of
EMT connecting them, then the fixtures themselves become a raceway and THHN is allowed
from the head fixture through the rest in the row).

scott
And thhn in a raceway on a "split" circuit (2 breakers tied together -
both sides of the service - 230 line to line) requires SEPARATE
NEUTRALS for each circuit, while NMD for the same application shares
the neutral. At least that was the requirement when we rewired the
new office.

Evidently for safety. You're less likely to find NMD on an office wall?

JustGuessing,
Bill
Some NMD and more BX. And the BX has the same requirements as NMD -
shared neutral is OK.

On 12/07/10 1:16 PM, wrote:
On Mon, 06 Dec 2010 23:02:40 -0500, wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.
2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

Why not use a 240V breaker, with 12/3, then there is no issue with tying
the handles, you still get two 120V circuits. Sounds safer to me, but
not sure about code.

--
Froz...


The system will be down for 10 days for preventive maintenance.

FrozenNorth wrote:
On 12/07/10 1:16 PM, wrote:

On Mon, 06 Dec 2010 23:02:40 -0500, wrote:

Scott Lurndal wrote:

writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).


I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott


Because???


Because 1) - it is code.
2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.


Why not use a 240V breaker, with 12/3, then there is no issue with tying
the handles, you still get two 120V circuits. Sounds safer to me, but
not sure about code.


That's normally what is done.

--
Jack Novak
Buffalo, NY - USA

On 12/07/10 2:09 PM, Nova wrote:
FrozenNorth wrote:
On 12/07/10 1:16 PM, wrote:

On Mon, 06 Dec 2010 23:02:40 -0500, wrote:

Scott Lurndal wrote:

writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).


I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott


Because???


Because 1) - it is code.
2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.


Why not use a 240V breaker, with 12/3, then there is no issue with
tying the handles, you still get two 120V circuits. Sounds safer to
me, but not sure about code.


That's normally what is done.

That is what I thought, split kitchen receptacles like that are common
(read code) in Canada, but I thought there was an issue with them in the
States, so I wasn't sure in this situation.

--
Froz...


The system will be down for 10 days for preventive maintenance.

Larry Jaques writes:
On 07 Dec 2010 03:26:49 GMT, (Scott Lurndal)
wrote:

Bill writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

NO! He wants two separate circuits for different rows of lights. If
one blows, your way would have him in complete darkness instantly.


Then don't recommend an edison circuit to him, which Lew apparently did.

s

On 12/7/2010 1:41 PM, FrozenNorth wrote:
On 12/07/10 1:16 PM, wrote:
On Mon, 06 Dec 2010 23:02:40 -0500, wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.
2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

Why not use a 240V breaker, with 12/3, then there is no issue with tying
the handles, you still get two 120V circuits. Sounds safer to me, but
not sure about code.


I think the original explanation provided was to "avoid cycling the
circuit breaker". I don't have a basis for an opinion on this.

Bill

On Tue, 07 Dec 2010 13:41:32 -0500, FrozenNorth
wrote:

On 12/07/10 1:16 PM, wrote:
On Mon, 06 Dec 2010 23:02:40 -0500, wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.
2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

Why not use a 240V breaker, with 12/3, then there is no issue with tying
the handles, you still get two 120V circuits. Sounds safer to me, but
not sure about code.
That's what is normally done - the 240 breaker is tied and co-trip

On 12/07/10 2:19 PM, Bill wrote:
On 12/7/2010 1:41 PM, FrozenNorth wrote:
On 12/07/10 1:16 PM, wrote:
On Mon, 06 Dec 2010 23:02:40 -0500, wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.
2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

Why not use a 240V breaker, with 12/3, then there is no issue with tying
the handles, you still get two 120V circuits. Sounds safer to me, but
not sure about code.


I think the original explanation provided was to "avoid cycling the
circuit breaker". I don't have a basis for an opinion on this.

Nothing stopping you from feeding two 120V switches with the 12/3, then
two separate runs of 12/2 to your fixtures.

--
Froz...


The system will be down for 10 days for preventive maintenance.

On 12/07/10 2:16 PM, Scott Lurndal wrote:
Larry writes:
On 07 Dec 2010 03:26:49 GMT, (Scott Lurndal)
wrote:

writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

NO! He wants two separate circuits for different rows of lights. If
one blows, your way would have him in complete darkness instantly.


Then don't recommend an edison circuit to him, which Lew apparently did.

Run a separate 120V to a single bulb in the center of the shop.

--
Froz...


The system will be down for 10 days for preventive maintenance.

On 12/07/10 2:59 PM, FrozenNorth wrote:
On 12/07/10 2:16 PM, Scott Lurndal wrote:
Larry writes:
On 07 Dec 2010 03:26:49 GMT, (Scott Lurndal)
wrote:

writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

NO! He wants two separate circuits for different rows of lights. If
one blows, your way would have him in complete darkness instantly.


Then don't recommend an edison circuit to him, which Lew apparently did.

Run a separate 120V to a single bulb in the center of the shop.

One other thought, how often does a dedicated lighting circuit actually
blow, not sure I have ever seen it happen. Not that it couldn't happen.

--
Froz...


The system will be down for 10 days for preventive maintenance.

Bill writes:
On 12/7/2010 1:41 PM, FrozenNorth wrote:
On 12/07/10 1:16 PM, wrote:
On Mon, 06 Dec 2010 23:02:40 -0500, wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.
2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

Why not use a 240V breaker, with 12/3, then there is no issue with tying
the handles, you still get two 120V circuits. Sounds safer to me, but
not sure about code.


I think the original explanation provided was to "avoid cycling the
circuit breaker". I don't have a basis for an opinion on this.


he is suggesting that you not use the breaker as a switch. Stick a switch
between the breaker and the load (which is de rigueur anyway).

scott

On 12/7/2010 2:56 PM, FrozenNorth wrote:

Nothing stopping you from feeding two 120V switches with the 12/3, then
two separate runs of 12/2 to your fixtures.


Thank you. That will leave my electical panel a little neater than
having two 12/2 runs starting there. Appreciate it!

Bill

FrozenNorth wrote:


Nothing stopping you from feeding two 120V switches with the 12/3,
then two separate runs of 12/2 to your fixtures.

I'll take the correction if I'm wrong, but doesn't the NEC require that you
downgrade the circuit if sharing a neutral?

--

-Mike-

Mike Marlow wrote:
FrozenNorth wrote:


Nothing stopping you from feeding two 120V switches with the 12/3,
then two separate runs of 12/2 to your fixtures.

I'll take the correction if I'm wrong, but doesn't the NEC require that you
downgrade the circuit if sharing a neutral?


Makes sense..I look forward to learning the answer.

Bill

Bill wrote:
Mike Marlow wrote:
FrozenNorth wrote:


Nothing stopping you from feeding two 120V switches with the 12/3,
then two separate runs of 12/2 to your fixtures.

I'll take the correction if I'm wrong, but doesn't the NEC require
that you
downgrade the circuit if sharing a neutral?


Makes sense..I look forward to learning the answer.

I meant to say, I'm curious. I have no sense of entitlement.



Bill

On 12/07/2010 06:40 PM, Bill wrote:
Mike Marlow wrote:
FrozenNorth wrote:


Nothing stopping you from feeding two 120V switches with the 12/3,
then two separate runs of 12/2 to your fixtures.

I'll take the correction if I'm wrong, but doesn't the NEC require
that you
downgrade the circuit if sharing a neutral?


Makes sense..I look forward to learning the answer.

Bill

As long as the two hots are of opposite phase, no problem.

On Tue, 7 Dec 2010 20:30:58 -0500, "Mike Marlow"
wrote:

FrozenNorth wrote:


Nothing stopping you from feeding two 120V switches with the 12/3,
then two separate runs of 12/2 to your fixtures.

I'll take the correction if I'm wrong, but doesn't the NEC require that you
downgrade the circuit if sharing a neutral?
Don't know about the NEC, but Ontario code does not require it.

On Tue, 07 Dec 2010 19:23:39 -0700, Doug Winterburn
wrote:

On 12/07/2010 06:40 PM, Bill wrote:
Mike Marlow wrote:
FrozenNorth wrote:


Nothing stopping you from feeding two 120V switches with the 12/3,
then two separate runs of 12/2 to your fixtures.

I'll take the correction if I'm wrong, but doesn't the NEC require
that you
downgrade the circuit if sharing a neutral?


Makes sense..I look forward to learning the answer.

Bill

As long as the two hots are of opposite phase, no problem.
Not technically "opposite phase" as it is a single phase service
(center tapped transformer)

On 12/07/2010 08:24 PM, wrote:
On Tue, 07 Dec 2010 19:23:39 -0700, Doug Winterburn
wrote:

On 12/07/2010 06:40 PM, Bill wrote:
Mike Marlow wrote:
FrozenNorth wrote:


Nothing stopping you from feeding two 120V switches with the 12/3,
then two separate runs of 12/2 to your fixtures.

I'll take the correction if I'm wrong, but doesn't the NEC require
that you
downgrade the circuit if sharing a neutral?


Makes sense..I look forward to learning the answer.

Bill

As long as the two hots are of opposite phase, no problem.
Not technically "opposite phase" as it is a single phase service
(center tapped transformer)

OK, the two hots are 180 degrees out of phase with respect to the
center-tap/neutral/ground.

At any rate, if identical loads are present on each hot, there will be
no neutral current.

On Tue, 07 Dec 2010 13:16:11 -0500, wrote:

On Mon, 06 Dec 2010 23:02:40 -0500, Bill wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.

Show me code in any country which demands tied circuit breaker handles
for 120v circuits. I double dog dare you!


2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

We're talking 120v here, not 240, clare. With 240v, both phases are
going to the same box. Here, there are separate circuits and boxes
with a single phase going to each.

--
You can't wait for inspiration. You have to go after it with a club.
--Jack London

On Tue, 07 Dec 2010 21:06:47 -0700, Doug Winterburn
wrote:

OK, the two hots are 180 degrees out of phase with respect to the
center-tap/neutral/ground.

At any rate, if identical loads are present on each hot, there will be
no neutral current.

If the phase is 180 degres out of phase and you add them together you
have no potential!

Mark

On 12/08/2010 06:32 AM, Markem wrote:
On Tue, 07 Dec 2010 21:06:47 -0700, Doug Winterburn
wrote:

OK, the two hots are 180 degrees out of phase with respect to the
center-tap/neutral/ground.

At any rate, if identical loads are present on each hot, there will be
no neutral current.

If the phase is 180 degres out of phase and you add them together you
have no potential!

Mark

....on the neutral.

On 12/08/2010 06:32 AM, Markem wrote:
On Tue, 07 Dec 2010 21:06:47 -0700, Doug Winterburn
wrote:

OK, the two hots are 180 degrees out of phase with respect to the
center-tap/neutral/ground.

At any rate, if identical loads are present on each hot, there will be
no neutral current.

If the phase is 180 degres out of phase and you add them together you
have no potential!

Mark

Try this:

http://en.wikipedia.org/wiki/Split-phase_electric_power

Larry Jaques wrote:

I started with four 8-foot two lamp fixtures w/ mag ballast over
a decade ago. I think the fixtures were about $30 each. Last
year, I replaced all the ballasts with Advance electronics (at
about $25 ea). More than enough light. Use C50's.

Shop is 20x25.

Larry,

Scott Lurndal used four 8' fixtures too (32' of lighting).

That basically equates to eight 4' fixtures (32' of lighting. Lew's High
Intensity Lighting Sketch (LHITS) gives sixteen 4' fixtures divided onto
2 circuits. That is, 32' per circuit. So on one level, there is
unanimous agreement. I couldn't quite install sixteen fixtures, even if
I wanted to, due to my attic access. However, in its favor, the LHITS
model does provide an extra level of service (should I be in sales?).

A factor I was willing to overlook when I first started thinking about
installing lighting was "uniformity" in lighting. I guess that takes
things to a more professional standard. My original configuration would
have been powered by duplex outlets, and would would have been a highly
reconfigurable system, so there would not have been a real
commitment/investment. No so true at the current level.

I may hang a few fixtures, partly for the fun of nailing together some
8' twobyfour scaffolding (I want to Build, BUIld, BUILD!! with veins in
my teeth!)!!! ~ Arlo Guthrie. There's No Way anything could go wrong
in a small 8' high project like that! Maybe I'll post a picture, but I
don't wish for anyone with a license to look at it!

Okay, I'm off to work! I hope I left ya something to smile about! : )

Bill

Bill wrote:


That basically equates to eight 4' fixtures (32' of lighting. Lew's
High Intensity Lighting Sketch (LHITS) gives sixteen 4' fixtures
divided onto 2 circuits. That is, 32' per circuit. So on one level,
there is unanimous agreement. I couldn't quite install sixteen
fixtures, even if I wanted to, due to my attic access. However, in
its favor, the LHITS model does provide an extra level of service
(should I be in sales?).

Categorically not!

A factor I was willing to overlook when I first started thinking about
installing lighting was "uniformity" in lighting. I guess that takes
things to a more professional standard. My original configuration
would have been powered by duplex outlets, and would would have been
a highly reconfigurable system, so there would not have been a real
commitment/investment. No so true at the current level.

Buy half of what you think you need and see how uniform it is. You're
getting carried away again Bill.


I may hang a few fixtures, partly for the fun of nailing together some
8' twobyfour scaffolding (I want to Build, BUIld, BUILD!! with veins
in my teeth!)!!! ~ Arlo Guthrie. There's No Way anything could go
wrong in a small 8' high project like that! Maybe I'll post a
picture, but I don't wish for anyone with a license to look at it!

Okay, I'm off to work! I hope I left ya something to smile about! : )


Have fun with the project. Nothing wrong with building. I bet you find
you've been making a mountain out of a mole hill here.

--

-Mike-

On Tue, 07 Dec 2010 20:17:50 -0800, Larry Jaques
wrote:

On Tue, 07 Dec 2010 13:16:11 -0500, wrote:

On Mon, 06 Dec 2010 23:02:40 -0500, Bill wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.

Show me code in any country which demands tied circuit breaker handles
for 120v circuits. I double dog dare you!


2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

We're talking 120v here, not 240, clare. With 240v, both phases are
going to the same box. Here, there are separate circuits and boxes
with a single phase going to each.



210.4 Multiwire Branch Circuits.
(A) General. Branch circuits recognized by this article
shall be permitted as multiwire circuits. A multiwire circuit
shall be permitted to be considered as multiple circuits. All
conductors of a multiwire branch circuit shall originate
from the same panelboard or similar distribution equipment.
FPN: A 3-phase, 4-wire, wye-connected power system
used to supply power to nonlinear loads may necessitate
that the power system design allow for the possibility of
high harmonic currents on the neutral conductor.
(B) Disconnecting Means. Each multiwire branch circuit
shall be provided with a means that will simultaneously
disconnect all ungrounded conductors at the point where
the branch circuit originates.
(C) Line-to-Neutral Loads. Multiwire branch circuits
shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies
only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the
multiwire branch circuit are opened simultaneously by the
branch-circuit overcurrent device.
FPN: See 300.13(B) for continuity of grounded conductor
on multiwire circuits.
(D) Grouping. The ungrounded and grounded conductors
of each multiwire branch circuit shall be grouped by wire
ties or similar means in at least one location within the
panelboard or other point of origination.
Exception: The requirement for grouping shall not apply if
the circuit enters from a cable or raceway unique to the
circuit that makes the grouping obvious.
ARTICLE 210—BRANCH CIRCUITS 210.4
2008 Edition NATIONAL ELECTRICAL CODE

Mike M

On Wed, 08 Dec 2010 13:49:54 -0500, Bill wrote:

Larry Jaques wrote:

I started with four 8-foot two lamp fixtures w/ mag ballast over
a decade ago. I think the fixtures were about $30 each. Last
year, I replaced all the ballasts with Advance electronics (at
about $25 ea). More than enough light. Use C50's.

Shop is 20x25.

Larry,

Scott Lurndal used four 8' fixtures too (32' of lighting).

Oops, missed that little detail. He has too much light for me.


That basically equates to eight 4' fixtures (32' of lighting. Lew's High
Intensity Lighting Sketch (LHITS) gives sixteen 4' fixtures divided onto
2 circuits. That is, 32' per circuit. So on one level, there is
unanimous agreement.

Between the two of them, yes.



I couldn't quite install sixteen fixtures, even if
I wanted to, due to my attic access. However, in its favor, the LHITS
model does provide an extra level of service (should I be in sales?).

9 (plus your original two) would be very bright.


A factor I was willing to overlook when I first started thinking about
installing lighting was "uniformity" in lighting. I guess that takes
things to a more professional standard.

Why the willingness?!? It makes things more comfortable, which
professionals strive for, too.


My original configuration would
have been powered by duplex outlets, and would would have been a highly
reconfigurable system, so there would not have been a real
commitment/investment. No so true at the current level.

If you go with Lew's suggestion, I want to hear all about it when you
find that you want to remove bulbs from some of the superfluous
fixtures 'cuz "It's too damned bright in here!" g


I may hang a few fixtures, partly for the fun of nailing together some
8' twobyfour scaffolding (I want to Build, BUIld, BUILD!! with veins in
my teeth!)!!! ~ Arlo Guthrie. There's No Way anything could go wrong
in a small 8' high project like that! Maybe I'll post a picture, but I
don't wish for anyone with a license to look at it!

Okay, I'm off to work! I hope I left ya something to smile about! : )

Again.

--
Invest in America: Buy a CONgresscritter today!

On Wed, 08 Dec 2010 14:39:26 -0800, Mike M
wrote:

On Tue, 07 Dec 2010 20:17:50 -0800, Larry Jaques
wrote:

On Tue, 07 Dec 2010 13:16:11 -0500, wrote:

On Mon, 06 Dec 2010 23:02:40 -0500, Bill wrote:

Scott Lurndal wrote:
writes:

To avoid "cycling the breakers", Lew advised running 12-3 from two 20
Amp breakers (it would not have occurred to me to do that).

I'm not sure what this means, but if you're running two 120v circuits
using 12-3 from a pair of 20A breakers, make sure the breaker handles
are tied together such that both trip if either one trips.

scott

Because???

Because 1) - it is code.

Show me code in any country which demands tied circuit breaker handles
for 120v circuits. I double dog dare you!


2) if one circuit trips and you assume the wire is "dead" you
could be - the black could be dead, and the red live, and a lifted
neutral (which is common to both) would be LIVE.

We're talking 120v here, not 240, clare. With 240v, both phases are
going to the same box. Here, there are separate circuits and boxes
with a single phase going to each.



210.4 Multiwire Branch Circuits.
(A) General. Branch circuits recognized by this article
shall be permitted as multiwire circuits. A multiwire circuit
shall be permitted to be considered as multiple circuits. All
conductors of a multiwire branch circuit shall originate
from the same panelboard or similar distribution equipment.
FPN: A 3-phase, 4-wire, wye-connected power system
used to supply power to nonlinear loads may necessitate
that the power system design allow for the possibility of
high harmonic currents on the neutral conductor.
(B) Disconnecting Means. Each multiwire branch circuit
shall be provided with a means that will simultaneously
disconnect all ungrounded conductors at the point where
the branch circuit originates.
(C) Line-to-Neutral Loads. Multiwire branch circuits
shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies
only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the
multiwire branch circuit are opened simultaneously by the
branch-circuit overcurrent device.
FPN: See 300.13(B) for continuity of grounded conductor
on multiwire circuits.
(D) Grouping. The ungrounded and grounded conductors
of each multiwire branch circuit shall be grouped by wire
ties or similar means in at least one location within the
panelboard or other point of origination.
Exception: The requirement for grouping shall not apply if
the circuit enters from a cable or raceway unique to the
circuit that makes the grouping obvious.
ARTICLE 210—BRANCH CIRCUITS 210.4
2008 Edition NATIONAL ELECTRICAL CODE

Mike, can you point out the particular text in that extract which
states the demand to tie two 120v breakers together when supplying
120v equipment?

--
Invest in America: Buy a CONgresscritter today!

Larry Jaques wrote:
On Wed, 08 Dec 2010 14:39:26 -0800, Mike M
wrote:

snip


210.4 Multiwire Branch Circuits.
(A) General. Branch circuits recognized by this article
shall be permitted as multiwire circuits. A multiwire circuit
shall be permitted to be considered as multiple circuits. All
conductors of a multiwire branch circuit shall originate

from the same panelboard or similar distribution equipment.

FPN: A 3-phase, 4-wire, wye-connected power system
used to supply power to nonlinear loads may necessitate
that the power system design allow for the possibility of
high harmonic currents on the neutral conductor.
(B) Disconnecting Means. Each multiwire branch circuit
shall be provided with a means that will simultaneously
disconnect all ungrounded conductors at the point where
the branch circuit originates.
(C) Line-to-Neutral Loads. Multiwire branch circuits
shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies
only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the
multiwire branch circuit are opened simultaneously by the
branch-circuit overcurrent device.
FPN: See 300.13(B) for continuity of grounded conductor
on multiwire circuits.
(D) Grouping. The ungrounded and grounded conductors
of each multiwire branch circuit shall be grouped by wire
ties or similar means in at least one location within the
panelboard or other point of origination.
Exception: The requirement for grouping shall not apply if
the circuit enters from a cable or raceway unique to the
circuit that makes the grouping obvious.
ARTICLE 210—BRANCH CIRCUITS 210.4
2008 Edition NATIONAL ELECTRICAL CODE


Mike, can you point out the particular text in that extract which
states the demand to tie two 120v breakers together when supplying
120v equipment?



For deciphering the 2008 code see:

http://www.inspectapedia.com/electric/multiwir.htm

--
Jack Novak
Buffalo, NY - USA

Mike Marlow wrote:
I bet you find
you've been making a mountain out of a mole hill here.

I hope so. But, from my vantage point, the part about how to wire a
bunch of fixtures in parallel, properly, was a decent-sized mole hill!
In my related reading, I'm finding the proper installation of EMT to be
a non-triviality (too). About all I can do (on my projects) is learn,
think and write about them until about mid-March. In (much) earlier
years, I would try to conceive, design and create a project on the same
day--preferably including finishing! Somewhere between then and now I
became more knowledgeable about, and subsequently impressed by, the
design process itself. When I was doing my drywall work this summer, it
seemed really "foreign" to me to realize I didn't need to save much of
my "design documentation". I'm accustomed to saving copies of almost
everything. You can see from the various people that make posts to this
thread that I'm far from the only one who reads and learns from your posts.

Bill

Bill wrote:
Mike Marlow wrote:
I bet you find
you've been making a mountain out of a mole hill here.

I hope so. But, from my vantage point, the part about how to wire a
bunch of fixtures in parallel, properly, was a decent-sized mole hill!
In my related reading, I'm finding the proper installation of EMT to
be a non-triviality (too). About all I can do (on my projects) is learn,
think and write about them until about mid-March. In (much) earlier
years, I would try to conceive, design and create a project on the
same day--preferably including finishing! Somewhere between then and
now I became more knowledgeable about, and subsequently impressed by,
the design process itself. When I was doing my drywall work this summer,
it seemed really "foreign" to me to realize I didn't need to save
much of my "design documentation". I'm accustomed to saving copies of
almost
everything. You can see from the various people that make posts to
this thread that I'm far from the only one who reads and learns from
your posts.


Oh hell - we all learn from each other's posts. The true beauty (and the
original intent...) of newsgroups. Wiring in conduit is nothing major.
Don't read into what you read too much. It's really straightforward stuff.
So... now that you're thinking about using conduit - go out and buy yourself
a 1/2" EMT bender. While away the hours between now and mid-March, studying
how to bend EMT, practicing it, learning how to quickly get rid of those
nasty pretzel bends that you'll be guaranteed to make in the beginning, and
by mid-March, you'll be up on your ladder hanging conduit. You'll love it -
it has such an industrial look. Really impresses the chicks...

--

-Mike-

Mike Marlow wrote:
However, in
its favor, the LHITS model does provide an extra level of service
(should I be in sales?).

Categorically not!

Come on now! Fly-by-night Enterprises has entrusted me, to show you,
the handy-est and the dandy-est tool you have ever seen. And don't
you wanna see how it works??? arms outstretched You get out the
patented pan, and you place the fish between the patented pans, and you
get out the tool which is not a slicer, it's not a dicer--it's not a
chopper-in-a-hopper...And what, dare you ask, could it possibly be??? ...

I actually worked retail for a few years in a big outdoor store. It was
okay at the time.

Bill

In article ,
Larry Jaques wrote:

On Wed, 08 Dec 2010 14:39:26 -0800, Mike M
wrote:
(B) Disconnecting Means. Each multiwire branch circuit
shall be provided with a means that will simultaneously
disconnect all ungrounded conductors at the point where
the branch circuit originates.

Mike, can you point out the particular text in that extract which
states the demand to tie two 120v breakers together when supplying
120v equipment?

I'm not mike, but that's what it says right there. "simultaneously
disconnect" is equivalent to, but more general than,"tied." Obviously
it's been edited over time (normal for code), since otherwise item C and
its exception #2 would not be relevant, having been required in item B...

Personal bias - just use a 240V breaker when you are contemplating
"tieing two together".

And if you want to fret about wire cost (the only real advantage to the
120/240V circuit), skip the neutral altogether and buy ballasts that
will run on 240V (more commonly these days, 85-277 or 120-277, without
taps) and run #14 wire (you've got half the amps to carry - you'll need
a lot of fixtures to warrant #12 and a 20 amp 240V circuit, .vs. #14 and
a 15 amp circuit.) At half an amp or so per 4-lamp F32T8 ballast at
240V, 24 ballasts (circuit derated to 80% for being on a long time) and
96 tubes (384 feet, if you like) on one circuit and 14 ga wire. For that
matter I'm danged if I know why folks are talking 12Ga wire on a
lighting-only circuit that might, at most, be 16 two-tube fixtures, and
probably won't even be that. Unless the ballasts are terrible (awful
power factor, inefficient) that should normally be well within the
capacity of a single 15 amp 120V circuit - and if being split in twain
so that they don't all go out at once (which, if it is really a lighting
only circuit, is far from likely in my experience, but I respect it as a
design goal) it's even more blatantly inside the reach of a 15 amp 120V
circuit to run half or 2/3's of that load on 14Ga wire.

I do overkill, but I try to avoid _stupid_ levels of overkill when it
costs me serious money. 20 amp breakers and/or 12ga wire to feed 2-lamp
4-foot fixtures in this quantity seems rather stupid, even for me - and
I have most of 1000 feet of 12-2NM I happened to buy back when it cost
$118.

--
Cats, coffee, chocolate...vices to live by

Mike Marlow wrote:

So... now that you're thinking about using conduit - go out and buy yourself
a 1/2" EMT bender.

Previous poster advised 3/4". I need to pull 8 #12 wires through. Which
size do you recommend?

Bill

Mike Marlow wrote:


Oh hell - we all learn from each other's posts. The true beauty (and the
original intent...) of newsgroups. Wiring in conduit is nothing major.
Don't read into what you read too much. It's really straightforward stuff.
So... now that you're thinking about using conduit - go out and buy yourself
a 1/2" EMT bender. While away the hours between now and mid-March, studying
how to bend EMT, practicing it, learning how to quickly get rid of those
nasty pretzel bends that you'll be guaranteed to make in the beginning, and
by mid-March, you'll be up on your ladder hanging conduit. You'll love it -
it has such an industrial look. Really impresses the chicks...


It would take me until mid-March to get one "box offset" done right. I
suck at bending conduit.

--
Jack Novak
Buffalo, NY - USA

In article , Bill
wrote:

Mike Marlow wrote:

So... now that you're thinking about using conduit - go out and buy yourself
a 1/2" EMT bender.

Previous poster advised 3/4". I need to pull 8 #12 wires through. Which
size do you recommend?

Bill

Reiterating what I said in another post, I find your defaulting to 12Ga
makes no sense when I think about what you are running on it (amperage
loads). As for conduit size, it's always easier to use larger conduit,
and costs little more for the extra ease and space. 1/2" is technically
fine for 8 12Ga THHN - that does not mean it will be a pleasant pull.

http://www.electrician2.com/calculat...alculator.html

I see no reason you can't run a 15 amp breaker (or breakers) and 14 ga
wire for the number of lights you are talking about (and I'm also a bit
confused about where you think you need 8 wires in one conduit for your
layout.)

--
Cats, coffee, chocolate...vices to live by

In article om,
Nova wrote:

It would take me until mid-March to get one "box offset" done right. I
suck at bending conduit.

For you (and others) they can be purchased as a complete die casting
with an EMT socket on one end and threads for the box on the other. Or
threads on both.

--
Cats, coffee, chocolate...vices to live by

Nova wrote:
Mike Marlow wrote:


Oh hell - we all learn from each other's posts. The true beauty (and
the original intent...) of newsgroups. Wiring in conduit is nothing
major. Don't read into what you read too much. It's really
straightforward stuff. So... now that you're thinking about using
conduit - go out and buy yourself a 1/2" EMT bender. While away the
hours between now and mid-March, studying how to bend EMT, practicing
it, learning how to quickly get rid of those nasty pretzel bends that
you'll be guaranteed to make in the beginning, and by mid-March,
you'll be up on your ladder hanging conduit. You'll love it - it has
such an industrial look. Really impresses the chicks...


It would take me until mid-March to get one "box offset" done right. I
suck at bending conduit.


Uh oh. LOL!
It's got to be easier than taping a decent drywall joint--at least I
hope it is! : )

Bill

Ecnerwal wrote:
- you'll need
a lot of fixtures to warrant #12 and a 20 amp 240V circuit, .vs. #14 and
a 15 amp circuit.) At half an amp or so per 4-lamp F32T8 ballast at
240V, 24 ballasts (circuit derated to 80% for being on a long time) and
96 tubes (384 feet, if you like) on one circuit and 14 ga wire. For that
matter I'm danged if I know why folks are talking 12Ga wire on a
lighting-only circuit that might, at most, be 16 two-tube fixtures, and
probably won't even be that. Unless the ballasts are terrible (awful
power factor, inefficient) that should normally be well within the
capacity of a single 15 amp 120V circuit - and if being split in twain
so that they don't all go out at once (which, if it is really a lighting
only circuit, is far from likely in my experience, but I respect it as a
design goal) it's even more blatantly inside the reach of a 15 amp 120V
circuit to run half or 2/3's of that load on 14Ga wire.

I do overkill, but I try to avoid _stupid_ levels of overkill when it
costs me serious money. 20 amp breakers and/or 12ga wire to feed 2-lamp
4-foot fixtures in this quantity seems rather stupid, even for me - and
I have most of 1000 feet of 12-2NM I happened to buy back when it cost
$118.

Please see if my math makes sense:

Amps/fixture = (32w + 32w)/120v .6.

So a 15 Amp circuit(derated 80% to 12) with 14ga wire may support
at least 12/.6 = 20 fixtures.

Should I be considering a "ballast surge" or anything like that (like
they have when an electric motor is first started)?

Bill

Bill wrote:
Nova wrote:

Mike Marlow wrote:


Oh hell - we all learn from each other's posts. The true beauty (and
the original intent...) of newsgroups. Wiring in conduit is nothing
major. Don't read into what you read too much. It's really
straightforward stuff. So... now that you're thinking about using
conduit - go out and buy yourself a 1/2" EMT bender. While away the
hours between now and mid-March, studying how to bend EMT, practicing
it, learning how to quickly get rid of those nasty pretzel bends that
you'll be guaranteed to make in the beginning, and by mid-March,
you'll be up on your ladder hanging conduit. You'll love it - it has
such an industrial look. Really impresses the chicks...


It would take me until mid-March to get one "box offset" done right. I
suck at bending conduit.


Uh oh. LOL!
It's got to be easier than taping a decent drywall joint--at least I
hope it is! : )

Bill


Let me put it this way... that Ecnerwal's advise in a previous post and
buy the die cast offset. He's also right about pulling 8 - #12's
through 1/2" EMT. The NEC allows 9 but it's a bitch if it's anything
other than a straight, short pull.

--
Jack Novak
Buffalo, NY - USA